MONDAY, March 7 (HealthDay News) -- Genetics may predispose some people who live in so-called "hazardous" neighborhoods -- where fear and stress are a fact of daily life -- to face a higher risk for age-related cognitive decline, new research warns.

The culprit is a specific abnormality of the apolipoprotein E gene. The study authors noted that while this gene is known to play a key role in the normal maintenance of basic neurological health, a certain mutation of this gene has also previously been linked to a higher risk for the early onset of Alzheimer's disease.

Now a team of researchers led by Brian K. Lee, of Drexel University in Philadelphia, has found that those carrying the mutation may also face a higher risk for cognitive impairment when they get older, if they live in the kind of threatening environment that routinely elicits "a biological stress response."

The observation is reported in the March issue of the Archives of General Psychiatry.

The new finding stems from an analysis of mental health data collected during the Baltimore Memory Study, which involved more than 1,100 urban residents living in 63 Baltimore neighborhoods.

All of the study participants were between the ages of 50 and 70. About 54 percent were white; nearly 42 percent were black.

As a whole, 30 percent were found to carry at least one mutation of the gene in question, the researchers found. However, blacks were more likely to carry the mutation than whites (37.3 percent versus 24.7 percent, respectively).

Genetics, in fact, wasn't the sole determinant of how well a person performed on cognitive tests. Any participant living in a stress-inducing environment, regardless of whether they possessed the mutation in question, performed "substantially" worse on the series of tests, which among other things included a focus on language skills, verbal memory and learning, eye-hand coordination and visual memory.

What's more, among those without the telltale mutation, those living in relatively more hazardous neighborhoods performed no worse on cognitive testing than those living in better neighborhoods. And among those with the mutation, those living in relatively better conditions executed the test skills equally well as those without the mutation, according to the study authors.

However, Lee's team found that those who carried the mutation, and also lived in neighborhoods characterized as the most psychosocially hazardous, performed the worst in terms of cognitive skills such as eye-hand coordination, task execution, processing speed and visual-spatial abilities.

More information

For more on mental health, visit the U.S. National Institute of Mental Health.